In the display advertising business, behavioral targeting (BT) is a popular method for building relationships with a target audience. Interest in utilizing BT in digital advertising businesses has been growing as advertisers are under constant pressure to achieve higher return on investments (ROI). Unfortunately, BT requires the ability to identify users within a network. Because of computer memory limitations, only a limited amount of user data is typically stored in the computer memory for fast retrieval. To deal with the resulting cache miss issues, many advertisers search secondary media (such as a data file on a hard disk) to find the missing user ID's data. However, as internet users become more diligent in refreshing cookies, the primary mechanism utilized by web sites to identify users, digital advertisers have struggled to maintain a targetable user inventory. Exacerbating the problem further, any time a user updates the browser or simply changes the language setting, the cookies are lost. As a result, after a one month period, it is approximated that nearly fifty percent of a targetable user inventory, utilizing cookies alone, is no longer available, making BT largely ineffective for digital advertising. Accordingly, maintaining a targetable user inventory so BT may be utilized in digital advertising is needed.